Transport vehicle system

ABSTRACT

A transport vehicle system includes a controller that controls transport vehicles that are able to travel along a track. When a travelling transport vehicle approaches a push out target vehicle, the controller performs push out control of transmitting a travel command to the push out target vehicle. In push out control, a push out point off planned travelling routes of all transport vehicles in a jurisdiction area is searched, and a command to travel to the push out point is transmitted as a travel command.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2018-228021 filed on Dec. 5, 2018. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a transport vehicle system.

2. Description of the Related Art

Conventionally, there has been known a transport vehicle system including a controller that controls multiple transport vehicles that can travel along a predetermined route. In such a transport vehicle system, when a travelling transport vehicle approaches another transport vehicle that is stopped, push out control is performed to transmit a travel command to the other transport vehicle that is stopped.

As this type of technology, JP 2013-35670 A discloses a transport vehicle system that performs push out control in which a push out destination is specified, for example. In the transport vehicle system described in JP 2013-35670 A, a second transport vehicle that is located within a predetermined range from the current position of a first transport vehicle having a move command (transport command) and within a push out range that does not exceed the destination and that does not have a move command is detected and a push out destination is determined. Additionally, a third transport vehicle that is located within a range from the current position of the second transport vehicle to the push out destination of the second transport vehicle and that does not have a move command is detected and a push out destination is determined. If the third transport vehicle can arrive first at the push out destination and the second transport vehicle can arrive first at the destination except for the third transport vehicle, an instruction is given to the second transport vehicle and the third transport vehicle to travel to the push out destination.

In the transport vehicle system as described above, there may be a situation where another transport vehicle approaches a transport vehicle moved by push out control immediately after the movement, that is, a situation where push out control is performed repeatedly, for example. In such a case, the transport vehicle subject to push out control (hereinafter also referred to as “push out target vehicle”) repeats travelling and stopping. Hence, the transport vehicle travelling behind the vehicle must decelerate, and transport efficiency may be decreased. Additionally, energy may be consumed wastefully.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide transport vehicle systems that each prevent repetition of push out control, and prevent a decline in transport efficiency and also prevent wasteful energy consumption.

A transport vehicle system according to a preferred embodiment of the present invention includes a controller that controls multiple transport vehicles capable of travelling along a predetermined route. When a travelling transport vehicle approaches another transport vehicle that is stopped, the controller performs push out control of transmitting a travel command to the other transport vehicle that is stopped. In the push out control, a push out point off planned travelling routes of all transport vehicles in a predetermined area is searched, and a command to travel to the push out point is transmitted as the travel command.

In the transport vehicle system, when a travelling transport vehicle approaches a push out target vehicle, push out control is performed, and the push out target vehicle is moved to a push out point off the planned travelling routes of all the transport vehicles in a predetermined area. In this way, by setting the push out point to a point off the planned travelling routes of all the transport vehicles, it is possible to avoid a situation where push out control needs to be performed repeatedly. That is, it is possible to prevent repetition of push out control, and to prevent a decline in transport efficiency and prevent wasteful energy consumption.

In a transport vehicle system according to a preferred embodiment of the present invention, the push out point may be a point before a branch point in the route. As a result, when a new command is assigned to a push out target vehicle moved to a push out point by push out control, and the push out target vehicle heads for the next destination, for example, the number of travelling route options for going to the next destination is able to be increased.

In a transport vehicle system according to a preferred embodiment of the present invention, in push out control, a return route to return from the searched push out point to a stop point of the other transport vehicle may be acquired, a score evaluating ease with which the acquired return route returns to the stop point may be calculated based on at least one of a distance, a required travel time, and a route cost of the return route, and a command to travel to the push out point when the calculated score is less than a threshold may be defined as the travel command. As a result, the push out target vehicle moved to the push out point by push out control is able to return relatively quickly to the stop point where it has been stopped before being moved. That is, it is possible to increase the possibility that the push out target vehicle can execute the transport command that the push out target vehicle has been about to execute before the movement (the possibility that a transport command is assigned).

In a transport vehicle system according to a preferred embodiment of the present invention, in the search for the push out point in the push out control, a route in the predetermined area may be traced frontward in a travelling direction from a stop point of the other transport vehicle, when a point off planned travelling routes of all transport vehicles in the predetermined area is found, a point based on the found point may be set as the push out point, and when the point off the planned travelling routes of all the transport vehicles in the predetermined area is not found within a predetermined distance from the stop point, a point based on a point that is a predetermined distance away from the stop point may be defined as the push out point. As a result, when a point off the planned travelling routes of all the transport vehicles does not exist within a predetermined distance from the stop point of the push out target vehicle, the push out target vehicle is moved to a push out point based on a point a predetermined distance away from the stop point. Thereafter, the push out target vehicle is moved again by the next push out control. In other words, when it is difficult to search for a point off the planned travelling routes of all the transport vehicles by push out control at the present moment, it can be searched again later by push out control that is performed again under changed route conditions.

According to preferred embodiments of the present invention, it is possible to provide a transport vehicle system that is able to reduce or eliminate repetition of push out control, and prevent a decline in transport efficiency and prevent wasteful energy consumption.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram showing a transport vehicle system according to a preferred embodiment of the present invention.

FIG. 2 is a flowchart showing processing performed by a controller of FIG. 1.

FIG. 3 is a flowchart showing processing of push out control.

FIG. 4 is a flowchart showing push out point search processing.

FIG. 5 is a flowchart showing a continuation of FIG. 4.

FIG. 6A is a schematic plan view for describing an example of push out control by the transport vehicle system of FIG. 1; FIG. 6B is a schematic plan view showing a state continued from FIG. 6A.

FIG. 7A is a schematic plan view showing a state continued from FIG. 6B; FIG. 7B is a schematic plan view showing a state continued from FIG. 7A.

FIG. 8A is a schematic plan view showing a state continued from FIG. 7B; FIG. 8B is a schematic plan view showing a state continued from FIG. 8A.

FIG. 9A is a schematic plan view showing a state continued from FIG. 8B; FIG. 9B is a schematic plan view showing a state continued from FIG. 9A.

FIG. 10A is an example showing a case where there are multiple push out points whose return route score is less than a threshold. FIG. 10B is a table showing processing results of push out control in the case of FIG. 10A.

FIG. 11A is an example showing a case where the priority of a push out point whose return route score is less than a threshold is low; FIG. 11B is a table showing processing results of push out control in the case of FIG. 11A.

FIG. 12A is an example showing a case where there is no push out point whose return route score is less than a threshold;

FIG. 12B is a table showing processing results of push out control in the case of FIG. 12A.

FIG. 13 is a table exemplifying push out points.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional proportions in the drawings do not necessarily coincide with those in the description.

As shown in FIGS. 1 and 2, a transport vehicle system 1 defines a system for transporting articles. The article is a container that stores multiple semiconductor wafers, for example, but may be a glass substrate, a general component, or the like. The transport vehicle system 1 includes a track 4, a transport vehicle 6, and a controller 50.

The track 4 is a predetermined route on which the transport vehicle 6 travels. The track 4 is laid near the ceiling, which is an overhead space of an operator, for example. The track 4 is suspended from the ceiling. Multiple point marks are attached to the track 4 so as to be positioned at regular intervals along the extending direction of the track 4. Examples of the point mark include a barcode. The track 4 includes straight and curved routes. For each route defining the track 4, a route cost related to an estimated time required to pass, for example, is set in advance.

The route of the track 4 is a one-way route in which the transport vehicle 6 travels only in one direction. The track 4 includes a branch point P that is a point dividing one route into multiple routes. Each of one route proceeding to one side and the other rout proceeding to the other side through the branch point P is set with a travelling priority. The transport vehicle 6 travels preferentially to one of the one route and the other route that has a higher priority. Note that the layout of the track 4 is not particularly limited, and various layouts can be adopted.

The transport vehicle 6 is a vehicle that is able to travel along the track 4, that is, a vehicle that can travel along a predetermined route. The transport vehicle 6 transports an article. The transport vehicle 6 is an overhead travelling unmanned transport vehicle. The transport vehicle 6 is also referred to as a carriage (transport carriage), an overhead travelling vehicle (overhead travelling carriage), or a travelling vehicle (travelling carriage), for example. The number of transport vehicles 6 included in the transport vehicle system 1 is not particularly limited, and there are multiple transport vehicles 6. The transport vehicle 6 is a linear motor driven vehicle, for example, and has an electromagnetic linear motor, for example, as a drive source. This allows the transport vehicle 6 to perform smooth and efficient acceleration/deceleration and high-speed continuous operation in short inter-vehicle distances.

The transport vehicle 6 includes a position acquisition unit (not shown) that acquires position information regarding the position of the transport vehicle 6 on the track 4. The position acquisition unit includes a reader that reads a point mark on the track 4, and the like. The position information on the transport vehicle 6 includes information on a point mark acquired by the reader, and information regarding a travel distance after passing the point mark, for example.

The controller 50 is an electronic control unit including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The controller 50 is able to be configured as software that is executed by the CPU by loading a program stored in the ROM on the RAM, for example. The controller 50 may be configured as hardware including an electronic circuit and other components. The controller 50 may be one device or multiple devices. When the controller 50 includes multiple devices, the devices are connected through a communication network such as the Internet or an intranet, so that one controller 50 is logically constructed.

The controller 50 performs periodic communication with multiple transport vehicles 6 in a jurisdiction area (predetermined area). For example, the controller 50 transmits a status query to the transport vehicle 6 in the jurisdiction area, and the transport vehicle 6 that receives the status query transmits a status report including its own position information, speed information, and the like to the controller 50. The controller 50 sequentially performs such communication with the multiple transport vehicles 6 in a periodic manner to grasp states (including the current position and whether the vehicle is stopped or travelling, for example) of the multiple transport vehicles 6 in the jurisdiction area. The jurisdiction area is not particularly limited. The size of the jurisdiction area may be set according to specifications or the like. For example, the jurisdiction area may be an entire area or a partial area of a system.

The controller 50 communicates with multiple transport vehicles 6 in a jurisdiction area, and controls the multiple transport vehicles 6. The controller 50 performs wired or wireless communication with a host controller (not shown). The controller 50 receives various commands from the host controller. For example, the controller 50 receives, from the host controller, a transport command to cause the transport vehicle 6 to transport the article. For example, the controller 50 receives, from the host controller, a move command to call (moving) the transport vehicle 6 to a predetermined position (e.g., an initial point of transport of a predicted transport command or a point before the initial point of transport). For example, the controller 50 receives, from the host controller, a circulation command to cause the transport vehicle 6 to circulate on a circulation route included in the track 4.

The controller 50 assigns the received transport command to an empty transport vehicle 6. An empty transport vehicle 6 is a transport vehicle 6 to which a transport command is not yet assigned, and includes an empty transport vehicle 6 that is not transporting an article. The controller 50 assigns the received move command or circulation command to an empty transport vehicle 6 to which various commands are not yet assigned.

The controller 50 reads layout data, which is data related to the layout of the track 4, and creates a route map of the track 4 from the layout data. The route map includes at least the route configuration, the travelling direction, the length of each route, and the priority order of the one route and the other route connected to the branch point P.

The controller 50 of the present preferred embodiment is configured or programmed to include a route searcher 51, a route manager 52, a storage 53, a push out target vehicle determiner 54, and a push out controller 55.

The route searcher 51 searches for a planned travelling route of each transport vehicle 6 in the jurisdiction area. A planned travelling route is a route on which the transport vehicle 6 plans to travel. The route searching method is not particularly limited, and various known methods can be used. For example, the route searcher 51 searches for a planned travelling route of each transport vehicle 6 based on at least a status report received from each transport vehicle 6, a command received from the host controller, and layout data that is data related to the layout of the track 4.

The route manager 52 manages the planned travelling routes (the planned travelling route of all the transport vehicles 6 in the jurisdiction area) searched by the route searcher 51. The storage 53 stores and periodically updates information related to the planned travelling route managed by the route manager 52. The storage 53 stores and periodically updates information related to the current position and state of each transport vehicle 6 in the jurisdiction area. The storage 53 stores information related to a route map of the track 4 created from layout data.

The push out target vehicle determiner 54 determines a push out target vehicle 6E (see FIGS. 6A and 6B), which is the transport vehicle 6 to be pushed out by push out control, based on pieces of information stored in the storage 53. The push out target vehicle 6E is another transport vehicle 6 stopped in front of the travelling transport vehicle 6, and is the transport vehicle 6 that approaches the travelling transport vehicle 6 until the inter-vehicle distance is equal to or shorter than a certain distance. Specific processing for determining the push out target vehicle 6E will be described later.

The push out controller 55 performs push out control on the determined push out target vehicle 6E. Push out control is control to move (push out) the push out target vehicle 6E so that the push out target vehicle 6E does not obstruct travel of the transport vehicle 6 approaching from behind. In push out control, in the jurisdiction area including the push out target vehicle 6E, a push out point off the planned travelling routes of all the transport vehicles 6 is searched, and a command to travel to the push out point is transmitted as a travel command.

A push out point is a push out destination point of push out control. The push out point is a point before the branch point P in the track 4. The distance from the push out point to the branch point P is a distance equal to or longer than a travel distance (e.g., 1 m to 2 m) necessary for the transport vehicle 6 to switch the travelling direction through the branch point P from one side to the other side.

In push out control, a return route to return from the searched push out point to the stop point of the push out target vehicle 6E is acquired, and a score evaluating ease with which the acquired return route returns to the stop point is calculated based on at least one of the distance, required travel time, and route cost of the return route. In push out control, a command to travel to the push out point when the calculated score is less than a threshold is defined as a travel command.

In the search for the push out point in push out control, the track 4 in the jurisdiction area is traced frontward in the travelling direction from the stop point of the push out target vehicle 6E. Then, when a point off the planned travelling routes of all the transport vehicles 6 in the jurisdiction area is found, the push out point is determined based on the found point. On the other hand, when a point off the planned travelling routes of all the transport vehicles 6 in the jurisdiction area is not found within a predetermined distance from the stop point, the push out point is determined based on a point that is a predetermined distance away from the stop point. The predetermined distance is determined in advance and stored in the storage 53. The predetermined distance is able to be appropriately changed by input of a user operation, for example. The predetermined distance is about 50 m, for example. Specific processing for searching for the push out point will be described later.

Next, an example of processing performed by the controller 50 will be specifically described with reference to the flowcharts of FIGS. 2 to 5.

First, the push out target vehicle determiner 54 searches for a stopped transport vehicle 6 from all the transport vehicles 6 in the jurisdiction area based on various information stored in the storage 53 (step S1). The push out target vehicle determiner 54 searches for the push out target vehicle 6E from the transport vehicles 6 that are stopped in the jurisdiction area based on various information stored in the storage 53 (step S2). For example, in step S2, based on the positions and travelling routes of all the transport vehicles 6 travelling in the jurisdiction area and the positions of all the transport vehicles stopped in the jurisdiction area, another stopped transport vehicle 6 that approaches the travelling transport vehicle 6 until the inter-vehicle distance is equal to or shorter than a certain distance is derived as the push out target vehicle 6E.

If the push out target vehicle 6E is not searched in step S2, the processing of this cycle is terminated, and the processing is repeatedly performed from step S1 in the subsequent cycle. If the push out target vehicle 6E is searched in step S2, the push out controller 55 performs the next push out control.

That is, the planned travelling routes and route maps of all the transport vehicles 6 in the jurisdiction area are acquired from the storage 53 (step S11). The acquired route map and the planned travelling route are collated (step S12). As a result, in all the routes included in the track 4, a non-travelled route that is a route off the planned travelling routes of all the transport vehicles 6 is identified. Push out point search processing to search for a push out point is performed (step S13, details will be described later).

A push out route that is a route to move to the push out point searched in step S13 is searched based on various information stored in the storage 53 (step S14). The route searching method in step S14 is not particularly limited, and various known methods can be used. A travel command to travel along the push out route to the push out point is generated, and the travel command is transmitted to the push out target vehicle 6E (step S15).

Here, the push out point search processing in step S13 will be described more specifically with reference to the flowcharts of FIGS. 4 and 5.

The search for the push out point is started (step S21). In step S21, the route starts to be traced along the travelling direction from the stop point of the push out target vehicle 6E until the branch point P is found. It is determined whether or not a new branch point P is found within the search distance (distance on the route from the stop position to the traced position) within a predetermined distance (step S22).

If YES in step S22, it is determined whether the found branch point P is on the non-travelled route identified in the verification in step S12, that is, whether the branch point P is off the planned travelling routes of all the transport vehicles 6 (step S23). If NO in step S23, the search for the push out point is continued (step S24).

In the continuation of the search, the one with a lower priority of the one route and the other route branching from the found branch point P is traced. In the continuation of the search, if the one with a lower priority of the one route and the other route has already been searched, the one with a higher priority of the one route and the other route is traced. In the continuation of the search, if both the one route and the other route have already been searched, the search is continued by going back to the previous branch point P on the upstream side. In the continuation of the search, if the search distance exceeds a predetermined distance, the search is continued by going back to the previous branch point P on the upstream side.

If YES in step S23, a point before the found branch point P is set as the push out point (step S25). It is determined whether or not the number of set push out points has reached a predetermined number (step S26). If NO in step S26, the processing proceeds to step S24. If YES in step S26, the search for the push out point is ended (step S27). If NO in step S22, the search for the push out point is ended (step S28). After step S28, it is determined whether there is no set push out point (step S29).

After step S27 or if NO in step S29, the return route for each of the multiple set push out points is acquired (step S31). The return route is a route to return from the searched push out point to the stop point of the push out target vehicle 6E. The return route is a route that connects two points, starting from the push out point and ending at the point where the push out target vehicle 6E is currently stopped. To acquire the return route, various known route search methods can be used.

A score of each return route is calculated (step S32). The score is an index to evaluate ease with which the push out target vehicle 6E returns to the stop point. The larger the score, the more difficult it is for the push out target vehicle 6E to return from the push out point to the stop point. The score is calculated based on at least one of the distance of the return route, the time required for the transport vehicle 6 to travel along the return route, and the route cost of the return route.

The greater the return route distance, the higher the score. The greater the time required for the transport vehicle 6 to travel along the return route, the higher the score. The higher the route cost set for the route forming the return route, the higher the score. For example, the route cost is set low for a route that is desirable to pass and is set high for a route that is not desirable to pass. The route cost is set high for routes that are prone to congestion. As the score and its calculation method, various known route evaluation indexes and their calculation methods can be used.

It is determined whether or not the calculated score is equal to or greater than a threshold (step S33, return route determination). As a result of the return route determination in step S33, it is determined whether or not the scores of all return routes are equal to or greater than a threshold (step S34).

If YES in step S34, the push out point set in the first step S25 is selected from the multiple push out points. The selected push out point is determined as the result of search of the push out point of the travel command by push out control (step S35). If NO in step S34, the push out point initially set in step S25 is selected from the multiple push out points of the return routes whose score is less than the threshold. The selected push out point is determined as the result of search of the push out point of the travel command by push out control (step S36).

On the other hand, if YES in step S29, a point before a branch point P whose search distance is within a predetermined distance and which has the longest search distance is set as a temporary point, and the temporary point is selected as the push out point (step S37). In other words, if a point off the planned travelling routes of all the transport vehicles 6 is not found on the track 4 under the condition that the search distance is within the predetermined distance, the push out point is selected based on a point that is a predetermined distance away from the stop point.

Next, an example of push out control including the above-mentioned push out point search processing will be described.

In the case shown in FIG. 6A, there are transport vehicles 61 and 62 that are travelling with a transport command assigned around the stopped push out target vehicle 6E. For example, the push out target vehicle 6E is stopped because: the push out target vehicle 6E has been called by a move command; the push out target vehicle 6E is waiting for another transport vehicle 6 to pass through the branch point P or the junction due to blocking control caused by the transport vehicle 6 ahead, or, it is determined that an abnormality has occurred. A transport vehicle 61 is approaching the push out target vehicle 6E from behind. A planned travelling route L1 of the transport vehicle 61 is a route that travels along a route R10 and travels to a route R12 through a branch point P1. A planned travelling route L2 of a transport vehicle 62 is a route that travels along a route R20, travels to a route R41 through a branch point P4, travels along the route R10 and a route R11, and travels to a route R22 through a branch point P2.

In push out point search processing in such a case, first, the route starts to be traced along the route R10 from the stop point of the push out target vehicle 6E, and the branch point P1 is found. The branch point P1 does not exist on a non-travelled route off the planned travelling routes L1 and L2, and therefore the search is continued. Here, since the route R11 has a lower priority than the route R12, the search is continued toward the route R11.

As shown in FIG. 6B, the route is traced from the branch point P1 along the route R11, and the branch point P2 is found. The branch point P2 does not exist on the non-travelled route off the planned travelling routes L1 and L2, and therefore the search is continued. Here, since a route R21 has a lower priority than the route R22, the search is continued toward the route R21.

As shown in FIG. 7A, the route is traced from the branch point P2 along the route R21, and a branch point P3 is found. The branch point P3 exists on the non-travelled route off the planned travelling routes L1 and L2. Hence, a point before the branch point P3 is set as a first push out point O1. The search is then continued to find the second push out point.

The search is continued by returning to the branch point P2, which is the previous branch point P. As a result of tracing the route from the branch point P2 along the route R22, the search distance exceeds a predetermined distance. Hence, the search is interrupted and the search is continued by returning to the branch point P1, which is the previous branch point P. As shown in FIG. 7B, the route is traced from the branch point P1 along the route R12, and the branch point P4 is found. The branch point P4 does not exist on the non-travelled route off the planned travelling routes L1 and L2, and therefore the search is continued. Here, since a route R42 has a lower priority than the route R41, the search is continued toward the route R42.

As shown in FIG. 8A, the route is traced from the branch point P4 along the route R42, and a branch point P5 is found. The branch point P5 exists on a non-travelled route off the planned travelling routes L1 and L2. Hence, a point before the branch point P5 is set as a second push out point O2.

Subsequently, as shown in FIG. 8B, return routes M1 and M2 from the respective push out points O1 and O2 to the stop point of the push out target vehicle 6E are acquired. The scores of the return routes M1 and M2 are calculated. Here, since the scores of the return routes M1 and M2 are both less than the threshold, as shown in FIG. 9A, the initially set push out point O1 is selected as the destination point of travelling by push out control. Thereafter, a normal route search is performed, and as shown in FIG. 9B, a push out route F for moving to the push out point O1 is searched. A travel command for travelling along the push out route F is transmitted to the push out target vehicle 6E.

As described above, in the transport vehicle system 1, when the travelling transport vehicle 6 approaches the push out target vehicle 6E, push out control is performed, and the push out target vehicle 6E is moved to the push out point O1 off the planned travelling routes of all the transport vehicles 6 in the jurisdiction area. In this way, the push out point O1 to be reached by performing push out control can be set to a point off the planned travelling routes of all the transport vehicles 6 (a location that does not interfere with any of the travelling transport vehicles 6). Hence, it is possible to avoid a situation where push out control needs to be performed repeatedly. In other words, it is possible to reduce or eliminate repetition of push out control, and to prevent a decline in transport efficiency and prevent wasteful energy consumption due to deceleration (acceleration) of the subject vehicle 6 subsequent to the push out target vehicle 6E.

In the transport vehicle system 1, the push out point O1 is a point before the branch point P on the track 4. Accordingly, when a new command is assigned to the push out target vehicle 6E moved to the push out point O1 by push out control, and the push out target vehicle 6E heads for the next destination, for example, the push out target vehicle 6E can travel on any of the one route and the other route through the branch point P. Thus, the number of travelling route options for going to the next destination is able to be increased.

In the transport vehicle system 1, in push out control, the return route M1 to return from the searched push out point O1 to the stop point of the push out target vehicle 6E is acquired. A score evaluating ease with which the acquired return route M1 returns to the stop point is calculated based on at least one of the distance, required travel time, and the route cost of the return route M1. A command to travel to the push out point O1 when the calculated score is less than the threshold is defined as a travel command. As a result, the push out target vehicle 6E moved to the push out point O1 by push out control can return relatively quickly (in a relatively short time) to the stop point where it has been stopped before being moved. It is possible to increase the possibility that the push out target vehicle 6E can execute the transport command that the push out target vehicle 6E has been about to execute before the movement (the possibility that a transport command is assigned).

In the transport vehicle system 1, in the search for a push out point O1 in push out control, the route of the track 4 in the jurisdiction area is traced to the front side in the travelling direction from the stop point of the push out target vehicle 6E. When a point off the planned travelling routes of all the transport vehicles 6 in the jurisdiction area is found, the push out point O1 is selected based on the found point. When a point off the planned travelling routes of all the transport vehicles 6 is not found within the search distance within the predetermined distance, the push out point is determined based on a point where the search distance is a predetermined distance. Specifically, a point before the branch point P having the longest search distance within the predetermined distance is determined as the push out point. As a result, when a point off the planned travelling routes of all the transport vehicles 6 is not found within the search distance within the predetermined distance, the push out target vehicle 6E is temporarily moved to a push out point based on the point where the search distance is a predetermined distance. Thereafter, the push out target vehicle 6E is moved again by the next push out control. In other words, when it is difficult to search for a point off the planned travelling routes of all the transport vehicles 6 by push out control at the present moment, it can be searched again later by push out control that is performed again under changed route conditions.

Note that the transport vehicle system 1 also has the following effects. As long as the transport vehicle 6 is stopped, it is possible to avoid hindrance of travel of the transport vehicle 6 to which a transport command is assigned, and transport capability is able to be improved. The number of executions of push out control is able to be reduced, and the risk of narrowing (clogging) the inter-vehicle distance from the rear transport vehicle 6 is able to be reduced. The push out target vehicle 6E is able to be kept as close as possible to the initially stopped location. By stopping after completion of transport, it is possible to reduce power consumption and contribute to energy saving.

Incidentally, in the above-described push out control, the push out point can be determined according to various cases or situations as exemplified below.

FIG. 10A is an example showing a case where there are multiple push out points whose return route score is less than the threshold. FIG. 10B is a table showing processing results of push out control in the case of FIG. 10A. For example, in the case of push out control shown in FIGS. 10A and 10B, branch points P1, P2, and P3 off the planned travelling routes of all transport vehicles 6 are found in this order. The points before the respective branch points P1, P2, and P3 are set as push out points A1, B1, and C1 in this order. As a result of performing the return route determination for each of the push out points A1, B1, and C1, the score of each return route of the push out points A1, B1, and C1 is less than the threshold (“success” in FIG. 10B). Hence, the push out point A1 having the earliest setting order is selected from the push out points A1, B1, and C1.

FIG. 11A is an example showing a case where the priority of the push out point whose return route score is less than the threshold is low. FIG. 11B is a table showing the processing results of push out control in the case of FIG. 11A. For example, in the case of push out control shown in FIGS. 11A and 11B, branch points P1, P2, and P3 off the planned travelling routes of all transport vehicles 6 are found in this order. The points before the respective the branch points P1, P2, and P3 are set as push out points A2, B2, and C2 in this order. As a result of performing the return route determination for each of the push out points A2, B2, and C2, the score of the return route of the push out point A2 is less than the threshold (“success” in FIG. 11B), but the score of each return route of the push out points B2 and C2 is equal to or greater than the threshold (“failed” in FIG. 11B). Hence, the push out point A2 of the return route whose score is less than the threshold is selected.

FIG. 12A is an example showing a case where there is no push out point whose return route score is less than the threshold. FIG. 12B is a table showing processing results of push out control in the case of FIG. 12A. For example, in the case of push out control shown in FIGS. 12A and 12B, branch points P1, P2, and P3 off the planned travelling routes of all transport vehicles 6 are found in this order. The points before the respective branch points P1, P2, P3 are set as push out points A3, B3, and C3 in this order. As a result of performing the return route determination for each of the push out points A3, B3, and C3, the score of each return route of the push out points A3, B3, and C3 is equal to or greater than the threshold (“failed” in FIG. 12B). Hence, the push out point A3 having the earliest setting order is selected from the push out points A3, B3, and C3.

FIG. 13 is a table exemplifying patterns of push out points. In the example shown in FIG. 13, push out points A, B, and C are set in this order. In FIG. 13, the return route determination result “success” means that the return route score is less than a threshold. The return route determination result “failed” means that the return route score is equal to or greater than the threshold.

As shown in pattern 1 of FIG. 13, as a result of push out control, when there is no push out point within a search distance within a predetermined distance, a point before the branch point P having the longest search distance is set as a temporary point, and the temporary point is selected as the push out point. As shown in pattern 2 of FIG. 13, as a result of push out control, when the push out point A is set and the return route determination result of the push out point A is “success”, the push out point A is selected.

As shown in pattern 3 of FIG. 13, as a result of push out control, when the push out point A exists and the return route determination result of the push out point A is “failed”, the push out point A is selected. As shown in pattern 4 of FIG. 13, as a result of push out control, when the push out points A and B exist, the return route determination result of the push out point A is “success”, and the return route determination result of the push out point B is “failed”, the push out point A is selected. As shown in pattern 5 of FIG. 13, as a result of push out control, when the push out points A and B exist, the return route determination result of the push out point A is “failed”, and the return route determination result of the push out point B is “success”, the push out point B is selected.

As shown in pattern 6 of FIG. 13, as a result of push out control, when the push out points A and B are set and the return route determination results of the push out points A and B are both “failed”, the push out point A is selected. As shown in pattern 7 of FIG. 13, as a result of push out control, when the push out points A, B, and C exist, the return route determination result of the push out point A is “failed”, and the return route determination results of the push out points B and C are “success”, the push out point B is selected. As shown in pattern 8 of FIG. 13, as a result of push out control, when the push out points A, B, and C exist and the return route determination results of the push out points A, B, and C are all “failed”, the push out point A is selected.

As mentioned above, while preferred embodiments of the present invention have been described, the present invention is not limited to the above preferred embodiments, and various changes can be made without departing from the gist of the present invention.

In the above preferred embodiments, an overhead travelling unmanned transport vehicle is preferably used as the transport vehicle 6, for example. However, the transport vehicle 6 is not particularly limited. The transport vehicle 6 may be an overhead travelling shuttle. The transport vehicle 6 may be a tracked unmanned transport vehicle that can travel along a track on the floor. The transport vehicle 6 may be a magnetic induction unmanned transport vehicle that can travel along a path made of magnetic tape or the like. The transport vehicle 6 may be a laser guided unmanned transport vehicle that can travel along a predetermined route by being guided by laser light.

In the above preferred embodiments, the transport vehicle 6 preferably includes an electromagnetic linear motor as a drive source, for example. However, the drive source of the transport vehicle 6 is not particularly limited. The transport vehicle 6 may include a normal rotary motor as a drive source. When the transport vehicle 6 is driven by a rotary motor, power is consumed if the motor moves continuously. Hence, the effect of reducing or eliminating repetition of push out control is significant.

In the above preferred embodiments, one or multiple other controllers that relay between the controller 50 and the transport vehicle 6 may be provided. The material and shape of each configuration in the above preferred embodiments are not particularly limited, and various materials and shapes are applicable.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A transport vehicle system comprising: a controller that controls a plurality of transport vehicles capable of travelling along a predetermined route; wherein when one of the plurality of travelling transport vehicles approaches another one of the plurality of transport vehicles that is stopped, the controller performs push out control of transmitting a travel command to the another one of the plurality of transport vehicle that is stopped; and in the push out control: a push out point off planned travelling routes of all transport vehicles in a predetermined area is searched; and a command to travel to the push out point is transmitted as the travel command.
 2. The transport vehicle system according to claim 1, wherein the push out point is a point before a branch point in the route.
 3. The transport vehicle system according to claim 1, wherein in the push out control: a return route to return from the searched push out point to a stop point of the another one of the plurality of transport vehicles is acquired; a score evaluating ease with which the acquired return route returns to the stop point is calculated based on at least one of a distance, a required travel time, and a route cost of the return route; and a command to travel to the push out point when the calculated score is less than a threshold is defined as the travel command.
 4. The transport vehicle system according to claim 1, wherein in the search for the push out point in the push out control: a route in the predetermined area is traced frontward in a travelling direction from a stop point of the another one of the plurality of transport vehicles; when a point off planned travelling routes of all transport vehicles in the predetermined area is found, a point based on the found point is set as the push out point; and when the point off the planned travelling routes of all the transport vehicles in the predetermined area is not found within a predetermined distance from the stop point, a point based on a point that is a predetermined distance away from the stop point is defined as the push out point. 